Flavivirus, including the West Nile virus, Dengue virus, Japanese encephalitis virus, Yellow fever virus, Zika virus and several other viruses, are single-stranded RNA virus which causes encephalitis. Among these viruses, Dengue virus (DENV) and Zika virus (ZIKV) are two of the arthropod-borne diseases that are seriously affecting many tropical and subtropical countries. DENV and ZIKV infections have similar geographical distribution and seasonal correlation because they share the same vectors of Aedes mosquitoes for transmission. Clinical manifestations of DENV infections are often indistinguishable from ZIKV infections, making clinical diagnosis difficult. Since DENV and ZIKV infection diseases pose a large threat to human's health for its high morbidity and mortality rate and there is no effective drug or vaccine up to date, early diagnosis of virus is essential for the early discovery and isolation of the patients to control the spread of said diseases.
Currently, the diagnoses of DENV and ZIKV are based on virus isolation cultures, ELISA, genomic RNA detection using PCR and fluorescent biosensor. Among these methods, fluorescent biosensing technology has received great interest in the detection of virus nucleic acids due to its merits of high sensitivity and rapid response time. Numerous materials such as carbon nanotubes (CNTs), carbon and Au nanoparticles (CNPs and AuNPs), graphene and graphene oxides (GO), MoS2 and WS2, as well as metal-organic frameworks (MOFs) have been employed as quenching platforms for fluorophore-labeled nucleic acid to eliminate the high background fluorescence for the determination of target nucleic acids with enhanced sensitivity (Kumar, P. et al., Trends Analyt. Chem. 73 (2015) 39-53, Zhu, X. et al, Chem. Commun. 49 (2013) 1276-1278, Zhang, H. T. et al., Chem. Commun. 50 (2014) 12069-12072). Such development is still at an infant stage and provided MOFs often suffer from a poor water stability and/or poor water stability significantly limiting their diagnostic use as a sensing platform. Further, those materials were mainly applied for the single detection of target nucleic acids. Simultaneous and synchronous detection for multiplexed nucleic acids is rarely reported (Ye, T. et al., Analyst 139 (2014) 1721-1725). Simultaneous and synchronous fluorescence analysis for multiple nucleic acids can not only shorten the analytical time, but also improve the detection sensitivity by avoiding the interference of Raleigh light scattering signal to the fluorescence signal of the fluorophore (Xiang, D. S. et al., Science China 56 (2013) 380-386). On the other hand, simultaneous and synchronous detection is important in clinical pre-diagnosis because some indistinguishable diseases, such as DENV and ZIKV, are associated with different nucleic acids and sequences, respectively.
Accordingly, there is a strong need for improved compounds which are easily obtainable in an economic way with sufficient water stability, water solubility and sufficient DNA or RNA binding ability which are suitable to form sensing platforms for target nucleic acid sequences such as in the diagnosis of viral infectious diseases, in particular for the simultaneous and synchronous detection of viral infectious diseases.